Pocketed spring cores or assemblies are commonly used in seating or bedding products. Such pocketed spring assemblies are commonly made of multiple strings or rows of individually pocketed springs. Adjacent strings of individually pocketed springs are joined together by gluing or otherwise attaching the fabric of the strings of springs to each other.
Pocketed coil springs are often referred to as a Marshall construction in which each coil spring is encased within its own fabric sack or pocket. The sack or pocket is typically defined between two plies of a fabric strip connected together at intervals along transverse lines of attachment spaced along the strip. The two-ply fabric strip is generally formed by folding a strip of double width fabric upon itself along a longitudinal centerline, leaving the overlapped plies along the unjoined opposite edges of the strip to be connected to each other along a longitudinal seam. After the springs are inserted between the plies, opposed plies are joined along transverse lines of attachment to close the pockets and separate adjacent springs.
A variety of techniques have evolved for the manufacture of pocketed springs, some contemplating the creation of the pockets within the fabric plies prior to insertion of the wire spring and others contemplating the insertion of compressed wire springs between the plies of the strip and the subsequent creation of the pockets by joining the two plies to each other along transverse lines of attachment between adjacent springs. In recent times, heat sensitive fabric and ultrasonic welding techniques have been utilized to join the fabric plies together along the seams or lines of attachment.
Most seams separating adjacent individually pocketed springs are linear, such as those disclosed in U.S. Pat. No. 6,826,796. In theory, a load placed upon the pocketed spring moves straight up and down along a vertical axis. However, in reality, the load placed upon a pocketed spring is often angled relative to the axis of the spring. Such an angled load may cause the pocketed spring to try to buckle and create stress on the fabric of the pocket. Over time, the fabric may wear and eventually break, causing the pocketed spring to move outside the pocket.
It is therefore an objective of this invention to provide a seating or bedding product which has a pocketed spring assembly which allows the springs inside the pockets to buckle without stressing the fabric of the pockets.
Still another objective of this invention is to provide a seating or bedding product which has a pocketed spring assembly having increased comfort due to ability of the springs inside the pockets to buckle.